1,720,969 research outputs found
Chemical composition of the essential oil of Brachyapium dichotomum (L.) Maire
Full text linkThe essential oil obtained by hydrodistillation from the aerial parts of Brachyapium dichotomum (L.) Maire
(Apiaceae), was analyzed by GC-MS for the first time. Sixty-two compounds were detected, accounting for 96.1% of
the total oil, which is characterized by a high content of hydrocarbons derivatives of mono- and sesquiterpenes
(80.3%). The main constituents were α-pinene (36.5%), germacrene D (17.9%), dill apiole (6.7%) and myristicin
(3.5%)
Antioxidant, anticholinesterase, and antibacterial activities of essential oils and methanol extract of Carduncellus pinnatus (Desf.)DC. growing in Algeria
No full textThe essential oil was obtained by separate hydrodistillation from the aerial parts of Carduncellus pinnatus (Desf.) DC. (Asteraceae) and was analyzed by means of gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS). Hundred and four compounds were detected, accounting for 95.29 % of the total oil, which is characterized by a high content of non-terpene derivatives (33.39%) and oxygenated sesquiterpenes (32.03%). The main constituents of the essential oil from the aerial parts were caryophyllene oxide (23.12%), (E)-2-hexenal (8.35%), (E)-β-ionone (6.01%), (E)-geranylacetone (2.96%), and nonanal (2.65%). Additionally, β-Carotene-linoleic acid test system, DPPH free radical scavenging assay and ABTS cation radical scavenging assay were tested for the study of antioxidant activity of plant methanol extract and essential oil. The MeOH extract of aerial parts exhibited a strong antioxidant activity evidenced by the ABTS cation radical scavenging assay, with IC50 values of 44.509 ± 1.149 μg/ml. In the DPPH test the IC50 values were 61.147 ± 0.924μg/ml, while in β-carotene-linoleic acid test system, the IC50 values were 153.744 ± 3.39μg/ml. Essential oil extract of aerial parts showed 81.80 c/o inhibition against butyrylcholinesterase at 200 μg/mL. The highest antibacterial activity was evidenced for the aerial parts MeOH extracts, with inhibition zone medium diameters of 18.66±1.00 mm against Escherichiacoli ATCC25922 at 16 mg/ml and of and 18.00±1.15mm against Micrococcus luteus ATCC533 at 16 mg/ml. This is the first report about the potential for food and pharmaceutical industry due to the composition and the biological activities of Carduncellus pinnatus essential oils growing in Algeria
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Rhanteriol, a New Rhanterium suaveolens Desf. Lignan with Pharmacological Potential as an Inhibitor of Enzymes Involved in Neurodegeneration and Type 2 Diabetes
Full text linkSeveral specialized plant metabolites are reported to be enzyme inhibitors. In this investigation, the phytochemical composition and the biological activity of Rhanterium suaveolens Desf. were studied. One new lignan (rhanteriol 1) and seven known secondary metabolites were isolated from the aerial parts of R. suaveolens by using different chromatographic procedures. The biological properties of the R. suaveolens extracts and the new compound were evaluated by measuring their ability to inhibit the cholinesterase and carbohydrate-hydrolyzing enzymes, using cell-free in vitro methods. The new lignan, rhanteriol, was shown to inhibit alpha-amylase and alpha-glucosidase (IC50 = 46.42 +/- 3.25 mu M and 26.76 +/- 3.29 mu M, respectively), as well as butyrylcholinesterase (IC50 = 10.41 +/- 0.03 mu M), with an effect comparable to that of the respective standards, acarbose and galantamine. Furthermore, docking studies were performed suggesting the interaction mode of rhanteriol with the active sites of the investigated enzymes. The obtained data demonstrated that the aerial part of R. suaveolens could represent a source of active molecules, such as rhanteriol, usable in the development of treatments for preventing or treating type 2 diabetes mellitus and neurodegeneration
Chemistry, antioxidant and anticholinesterase activity of the essential oil of Hippomarathrum libanotis Koch.
No full text..
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
